Your signature helps me help you, bunches. Thanks. And for pics, there's some info in Bullnose Forum/Forum FAQ's about that.
If you look at the snippet below of Ford's Master Parts Catalog from our page on Brakes you can see that there are two F250's. One is what I call the F250 LD since the other is what Ford called the F250 HD. The LD didn't have a full floating rear axle and was more like a 5/8 than a 3/4 ton truck.
But yours has to be the HD version because they didn't put either the 460 or the diesel in the LD. So I've highlighted that you have 12 x 3" brakes.
Gary, AKA "Gary fellow":
Profile
Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI